The development of HIV vaccines and other prevention strategies relies on the use of nonhuman primates in preclinical studies to advance the development of effective AIDS vaccine candidates and to advance development of effective topical microbicides and other prevention modalities or immune-based therapies. The NIAID Simian Vaccine Evaluation Unit (SVEU) contracts shall provide nonhuman primate resources that primarily support preclinical evaluation of AIDS vaccines. The SVEUs conduct studies in support of vaccines being developed by a wide range of investigators. These studies complement NIAID-supported basic vaccine research and vaccine evaluation studies funded through R01 (investigator-initiated research) grants, HIVRAD (HIV Vaccine Research and Design Program) grants, IPCAVD (Integrated Preclinical-Clinical AIDS Vaccine Development) grants, and NHP Consortium awards. The SVEUs also perform studies of candidate vaccines offered by companies or other researchers. Previous studies investigating immunization regimens using HIV or SIV gag and env immunogens in macaques and have found that DNA+protein co-delivery increases the magnitude and longevity of systemic and mucosal humoral immune responses to vaccines. The studies have found that the DNA+protein co-delivery vaccine regimen combines the strength of each individual vaccine component and induces robust cellular responses as well as long-lasting humoral immunity. The regimen improves magnitude breadth, mucosal dissemination as well as protective effects of the induced immune responses.